The U.S. Gulf Coast is getting a major soaking this weekend from Tropical Storm Lee. The storm is expected to dump as much as 50 centimeters of rain in parts of the southern states of Louisiana, Mississippi and Alabama.

With Tropical Storm Lee bearing down on the U.S. Gulf Coast, authorities are taking action.

Oil and gas producers shut down platforms and evacuated workers from the Gulf, and the governors of Mississippi and Louisiana declared states of emergency.

Louisiana Governor Bobby Jindal warned of the potential for flooding. "This is going to be a slow moving storm. There's going to be a lot of rain, and that water is going to accumulate. And I think the biggest concern is that you're going to have an accumulation of water because that water is going to pile up, it's going to come so quickly and for such a long time it's not going to be able to drain," he said.

One of the areas at risk is the Louisiana city of New Orleans. The city is more than two meters below sea level and shaped like a bowl, making it prone to flooding.

In 2005, New Orleans suffered devastating damage from Hurricane Katrina, and Mayor Mitch Landrieu is urging residents to be ready for Lee. "We are all prepared and should prepare for localised flooding and we've taken all necessary precautions to do that, and we're encouraging citizens in New Orleans to make their preparations. Again, you know, prepare for the worst and let's hope for the best," he said.

National Hurricane Center spokesman Dennis Feltgen says rain is the biggest worry for the city. "The good news for the New Orleans area and all along the southern Louisiana coastline is that we do not expect hurricane force winds such as we saw six years ago with Katrina. However, we do have a concern with the heavy rainfall, so their drainage systems and sewer systems and everything have a lot of water to handle, and I know the emergency managers have their hands full watching that," he said.

And even though Lee's winds will not reach hurricane strength, Feltgen says they could still pose a risk. "Tropical storm conditions, tropical storm force winds are going to be impacting all of the warning area today, and on top of that, a few tornadoes are possible from southern Louisiana all the way to the far western panhandle of Florida as the storm drifts its way along the coastline," he said.

Lee is the 12th named storm of the Atlantic hurricane season. It is hitting the United States just a week after deadly Hurricane Irene ravaged the nation's east coast.

Forecasters are also monitoring Hurricane Katia, which regained hurricane status in the Atlantic on Friday, but is not currently a threat to any land area.

Experts predicted an active hurricane season this year, and Feltgen says conditions are right on target.